Secondary immunodeficiency can be defined as the occurrence of cellular or humoral immunodeficiency in an individual who had an intact immune system before the onset of the condition. These acquired forms of immunodeficiency result from a diverse number of environmental causes as a side effect of cytotoxic drugs, malignancy and malnutrition.

00:01
Let’s look at secondary
immunodeficiency.
00:03
This is immunodeficiency
caused by an external agent.
00:07
In contrast to primary immunodeficiencies
which are caused by gene defects.
00:13
So secondary immunodeficiency is defective
immunity caused by an external factor.
00:20
Could be cytotoxic drugs, radiation,
immunosuppressive drugs, malnutrition,metabolic and other diseases, tumors,
immaturity, pregnancy, aging or infection.
00:43
All of these things can lead
to secondary immunodeficiency.
00:48
Cytotoxic drugs for example, chemotherapy,
targets rapidly dividing cells.
00:56
This restricts the ability of hematopoietic
stem cells to produce progenitor cells.
01:03
This commonly results in neutropenia
- low levels of neutrophils.
01:09
It also inhibits lymphocyte proliferation
in response to antigen stimulation.
01:15
Radiation, for example environmental exposure, or radiotherapygiven for the treatment of tumors and other conditions;just like cytotoxic drugs, radiation can restrict the abilityof hematopoietic stem cells to produce progenitor cells.
And also inhibits lymphocyte proliferationin response to antigen stimulation.
Immunosuppressive drugs used to limittransplant rejection, autoimmune
disease and allergy, can also leadto secondary immunodeficiency.
For example, general immunosuppressiveagents such as glucocorticoids.
Monoclonal antibodies targeted to adhesion molecules, tocytokine receptors, to co-stimulatory molecules and so forth.
02:04
And inhibitors of signaling pathways such
as the immunosuppressive drug cyclosporine.
02:10
Malnutrition, metabolic and other diseases are
yet again a cause of secondary immunodeficiency.
02:20
Protein-calorie malnutrition and deficiency of
micronutrients such as vitamin A, zinc, iron,magnesium, selenium, and so on can impair the
immune response, particularly T-cell responses.
02:36
In diabetes mellitus, there is a impaired
neutrophil chemotaxis and phagocytosis, a reduceddelayed hypersensitivity skin test reaction
and poor lymphocyte proliferation responses.
02:52
In the disease, intestinal lymphangiectasia,
lymphocytes are passively lost into the intestine.
03:01
In contrast, in the disease nephrotic syndrome, proteins
particularly antibodies are lost into the urine.
03:10
In tumors, cancer metastases can distrupt
interactions in lymphoid tissues.
03:18
In leukemia and lymphoma, the tumor cells can “crowd
out” the development of the normal immune responses.
03:27
And in myeloma, antibodies are dominated
by the specificity of the malignant plasmacell at the expense of other antibody
specificities against common pathogens.

About the Lecture

The lecture Introduction – Secondary Immunodeficiency by Peter Delves, PhD is from the course Immunodeficiency and Immune Deficiency Diseases.

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